There are various approaches to improve data transmission rate in a wireless communication system. As an example, technologies for improving data transmission rate by applying a high order modulation or increasing a number of transmission/reception antennas and a frequency bandwidth have been recently developed. Particularly, increasing of the frequency bandwidth may efficiently increase the data transmission rate.
Examples of the method for increasing the frequency bandwidth may include a method of obtaining a new frequency bandwidth having a broad bandwidth or a method of logically combining frequency bandwidths having a narrow bandwidth. Regardless of how the frequency bandwidth increases, the obtained frequency bandwidth may be used in roughly two ways.
One way is newly designing of a physical channel, a transmit channel, a logical channel, and the like that are optimal to the obtained frequency bandwidth, to use the obtained frequency bandwidth. Another way is maintaining of a physical channel, a transmit channel, and a logical channel that are designed for component frequency bandwidths constituting the obtained frequency bandwidth, to use the obtained frequency bandwidth. This other way is referred to as carrier aggregation.
There are terminals being capable of using an entire obtained frequency bandwidth and terminals being incapable of using the entire obtained frequency bandwidth but using only each of component frequency bandwidths constituting the obtained frequency bandwidth, and thus, the communication system that uses the carrier aggregation may need to provide a high compatibility.